Distributed doherty amplifiers

Abstract

Doherty and distributed amplifier (DA) designs are combined to achieve, wideband amplifiers with high efficiency dynamic range. A modified Doherty amplifier includes a wideband phase shifter providing first and second outputs, a main amplifier coupled to the first output, an auxiliary amplifier coupled to the second output, and a wideband combining network combining the outputs in phase. A multi-stage DA has a main output and a termination port, and a phase delay module and transforming network allowing power at the termination port to be combined in phase with power at the main output. In one combination, one or more stages of the DA may comprise a Doherty amplifier. In another combination, a modified series-type Doherty amplifying system is achieved by cascading main and auxiliary DAs. In any combination, Doherty topology may include a bias control module.

1. An amplifying system having an amplifying system output comprising:
 a distributed amplifier comprising a distributed amplifier output and a distributed amplifier termination port; 
 a node electrically coupling the distributed amplifier output, the distributed amplifier termination port and the amplifying system main output; 
 a phase delay module electrically coupled between the distributed amplifier termination port and the node; 
 a first transformer circuit electrically coupled between the distributed amplifier termination port and the node, wherein the phase delay module and the first transformer circuit are electrically coupled in series with each other between the distributed amplifier termination port and the node. 
 
     
     
       2. The amplifying system of  claim 1 , further comprising a second transformer circuit comprising a second transformer circuit input and a second transformer circuit output, wherein the second transformer circuit input is electrically coupled to the node. 
     
     
       3. The amplifying system of  claim 2 , wherein the second transformer circuit is configured to perform impedance matching of a combined output signal with a load coupled to a main output of the high efficiency, distributed amplifying system. 
     
     
       4. The amplifying system of  claim 1 , wherein the first transformer circuit is configured to perform impedance matching. 
     
     
       5. The amplifying system of  claim 1 , wherein the phase delay module is configured to facilitate combining a distributed amplifier termination port signal in phase with a distributed amplifier output signal. 
     
     
       6. The amplifying system of  claim 1 , further comprising a second transformer circuit that is interposed in electrical communication between the distributed amplifier output and the node. 
     
     
       7. The amplifying system of  claim 6 , wherein at least one of the first transformer circuit and the second transformer circuit comprise impedance matching transformers. 
     
     
       8. The amplifying system of  claim 1 , wherein power at the node from the phase delay module output is configured to combine in phase with power at the node from the distributed amplifier output. 
     
     
       9. The amplifying system of  claim 1 , configured for at least one of radio and microwave frequency signal amplification. 
     
     
       10. The amplifying system of  claim 1 , wherein the phase delay module comprises a wideband circuit. 
     
     
       11. The amplifying system of  claim 1 , wherein the amplifying system is embedded within a Doherty network. 
     
     
       12. The amplifying system of  claim 1 , wherein the distributed amplifier comprises a Hittite model HMC-C026 device. 
     
     
       13. The amplifying system of  claim 1 , wherein the distributed amplifier comprises a Doherty unit cell. 
     
     
       14. The amplifying system of  claim 13 , wherein the Doherty unit cell comprises a cascaded reactively terminated single-stage distributed amplifier. 
     
     
       15. The amplifying system of  claim 13 , wherein the Doherty unit cell comprises:
 a main amplifier having an output; 
 an auxiliary amplifier; and 
 a bias control module configured to automatically adjust an input bias to the auxiliary amplifier responsive to at least one of power detected at the output of the main amplifier or power detected to the input of the main amplifier. 
 
     
     
       16. The amplifying system of  claim 15 , wherein the bias control module samples the main distributed amplifier output power at a sampling frequency. 
     
     
       17. The amplifying system of  claim 15 , wherein the bias control module is configured to adjust the bias voltage based on sensing of a DC current to the auxiliary amplifier and to determine a compression point based on the sensed DC current. 
     
     
       18. The amplifying system of  claim 15 , wherein the bias control module is configured to automatically adjust the input bias to the auxiliary amplifier responsive to power detected at the output of the main amplifier absent detecting power at the output of the auxiliary amplifier. 
     
     
       19. The amplifying system of  claim 15 , further comprising a transforming network coupled to an auxiliary amplifier output configured for impedance matching. 
     
     
       20. A high efficiency, distributed amplifying system comprising:
 a distributed amplifier comprising a distributed amplifier input, a distributed amplifier output and a distributed amplifier termination port; 
 a phase delay module comprising a phase delay module input and a phase delay module output, wherein the phase delay module input is coupled to the distributed amplifier termination port; and 
 a first transformer circuit comprising a first transformer circuit input and a first transformer circuit output, wherein the first transformer circuit input is coupled to the phase delay module output, wherein the distributed amplifier output port is coupled to the first transformer circuit output via a node.